Valve for rock drills



May 22, 1928. 1,670,367

E. B. LEAR VALVE FOR ROCK DRILLS Filed April I927 01 dkbvr Y 5 9 INVENTOR.

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Patented May 22, 1928.

UNITED STATES PATENT OFFICE.

EARL B. LEAR, OF PHILLIPSBURG, NEW JERSEY, ASSIGNOR TO INGERSOLL-RAND OOMIPANY, 0F JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY.

VALVE FOR ROCK DRILLS.

Application filed April 9, 1927. Serial No. 182,828.

This invention relates to rock drills, but more particularly to a distributing valve for fluid actuated rock drills of the hammer type.

The objects of the invention are to obtain a durable valve of light weight, to effect a re id distribution of pressure fluid to the cy inder, and to hold the valve firmly in its extreme positions during the admission of pressure fluid to the cylinder.

Other objects will be in part obvious and in part pointed out hereinafter.

In the drawingsillustrating an embod1- ment of the invention,

Figure 1 is a longitudinal sectional elevation of a portion of a rock drill showing the valve in position to admit ressure fluid to the rearward end of the cylinder, and

Figure 2 is a view similar to Figure 1 showing the valve in its other limiting position.

Referring to the drawin s, the invention is shown embodied in a roc drill having a cylinder A closed at its front end by a bushing B and at its rearward end by a back head G. The cylinder A is provided with a hammer piston D which controls a free exhaust port E in the cylinder and has a. forwardly extending reduced shank F 'slidable in the bushing B. V

Formed on the cylinder A is a valve chest G having an annular bore H which extends from the rearward end of the chest to a point near the front end thereof, thus forming an end wall J in the chest G.

At the opening of the bore H is formed an annular recess K to receive a flange L of a bushing 0 having in this instance a passage P which communicates with a passage Q in the back head C. Preferably a throttle valve R of any suitable type is interposed in the passage Q, to control communication between the passage P and a source of ressure fluid supply (not shown).

In the f i'ont endzof the bore H is disposed a bushing S which abuts the wall J and has a threaded extension Tprojecting through the wall J to receive a nut U whereby the bushing S is securedfirmly in position. The bushin s O and S are bored to form a valve 0 amber V and are spaced to form an ing into the inlet passage Y and the face 6 enlarged portion X in the valve chamber V.

Pressure fluid for actuating the piston D is conveyed to the cylinder through inlet passages Y and Z leading from the rearward and front ends respectively of the valve chamber V to the corresponding ends of the cylinder A.

Disposed in the valve chamber V is a distributin valve 6 having in this instance a bore 0 tierethrough for conveying pressure fluid from the passage P to the inlet passage Z. The rearward and front ends d and 6 respectively of the valvetare preferably so formed as to enable them to lie flush a ainst' the adjacent ends 7 and g of the busdiings O and S.- The ends (1 and e when out of contact with their respective faces which they are intended to abut serve as holding faces against which pressure fluid may act for holding the valve in their extreme positions. For instance, with the valve in the position illustrated in Figure 1, the end face d is exposed to live pressure fluid flowis thus held firmly against the face 9 of'the bushing S.

Intermediate the ends of the valve is formed an enlarged flange h which reciprocates in the enlarged portion X of the valve chamber and thus divides the said enlarged portion into forward and rearward pressure chambers j and is into which pressure fluid is constantly conveyed from the interior of I the valve by leak ports 0 and p to act against forward and rearward surfaces 1 and 1' re spectively of the flange It. The end surfaces 9 and r of the flange h in this instance constitute both actuating and holding faces and are constantly subjected to pressure fluid under varying pressures;

In order to provide a controlled escape for the pressure fluid admitted into the pressure chambers j and k, said pressure chambers are provided with exhaust passages a and t which open into the cylinder A preferably at points near the free exhaust port E and are controlled by the piston D. I

The operation of the device is as follows: With the valve b in the position illustrated in Figure 1, pressure fluid flowing through v the inlet passage Y to the rearward endof the c linder will actuate the piston D forward y. As will be observed, at the beginning of the forward stroke of the piston D, the passage t will be covered thereby so that the pressure fluid flowing through the leak port p will be entrapped in the pressure chamber In and, acting against the surface r of the flange h, will hold the forward end 6 of the valve firmly against the end 9 of the valve chamber, thus sealing the front end of the valve. Any slight admission of pressure fluid, however, which may leak past the cooperating surfaces of the valve and the valve chamber may pass directly to the atmosphere through the free exhaust E, as may also the pressure fluid that enters the pressure chamber 7' while the valve is in this position. An additional holding effect is obtained while the valve is in its forward position by the pressure fluid acting against the end d during its passage from the passlage P into the rearward end of the cylin- Immediately prior to the opening of the free exhaust port E by the piston D, the rearward exhaust passage t will be uncovered by the piston so that the pressure fluid in the pressure chamber is may escape throu h these channels, along with the pressure fluid in the rearward end of the cylinder, to atmosphere.

Shortly before communication between the atmosphere and the pressure chamber is is established, the front exhaust passage 8 will be covered by the piston and the pressure fluid flowing into the pressure chamber 9' will then be entrapped therein and, acting against the surface 9 of the valve flange I will move the valve rearwardly to the position illustrated in Fi ure 2 at about the time the piston D delivers its blow to the working implement (not shown). By mov-.

ing the valve rearwardly, direct communication between the interior of the valve and the front end of the cylinder will have been established and the pressure fluid will then flow into the front end of the cylinder to drive the piston D rearwardly.

As will be apparent, the pressure fluid in the pressure chamber 7' will remain entrapped therein and, assisted by the pressure acting against the front end e of the valve, will hold the valve in its rearwardmost positionnntil communication between the passage s and the free exhaust port E is again established by the piston, whereupon the pressure fluid in the pressure chamber 7', together with the pressure fluid in the front end of the cylinder will be exhausted to the atmosphere, thus completing the cycle of operations.

I claim:

1. In a fluid actuated rock drill, the combination of a cylinder and piston, a valve chest having a valve chamber, a distributing valve in the valve chamber having a bore for conveying pressure fluid therethrough, the ends of said valve cooperating with the ends of the valve chamber for controlling the admission of pressure fluid to the cylinder, a flange on the valve having actuating and holding surfaces, ports constantly conveying pressure fluid into the valve chamber to act against the surfaces, and passages for exhausting such pressure fluid into the cylinder after the valve has been actuated.

2. In a fluid actuated rock drill, the combination of a cylinder and piston, a valve chest having a valve chamber, a distributing valve in the valve chamber having a bore for conveying pressure fluid therethrough the ends of said valve abutting the ends 0 the valve chamber to effect a reduction in pressure on one end of the valve while pressure fluid is flowing over the other end, a flange on the valve having opposed actuating and holding surfaces, ports in the valve conveying pressure fluid into the valve chamber to act against the surfaces for throwing the valve and for holding it in thrown position, and passages in the valve chest for exhausting such pressure fluid from the valve chamber into the cylinder, said passages being controlled by the piston.

3. In a fluid actuated rock drill, the combination of a cylinder and piston, a valve chest havin a valve chamber with an intermediate en arged valve chamber havlng a bore for conve ing pressure fluid therethrough, the ends 0 the valve constituting holding surfaces and cooperatin with the ends of the valve chamber to e ect a reduction of presure on one end while the other end is exposed to pressure fluid, a central flange on the valve dividin the enlarged portion of the valve cham er into pressure chambers, ports in the valve constantly conveying pressure fluid into the pressure chambers to actuate the valve, exhaust passages leading from the pressure chambers to the cylinder, and a free exhaust port in the cylinder, said exhaust passages and exhaust ports being controlled y the piston.

In testimony whereof I have signed this specification.

EARL B. LEAR.

ortion, a valve in the 

